Yamaha - Gear 2 - Lower Unit Gearcase Component - 6H4-45571-01-00

Overview

When you’re dealing with gearcase issues, it’s usually not something minor, and gears like this are right at the center of it. I’ve torn down lower units where worn or chipped gears were the reason for noise, slipping, or failure to stay in gear. It’s not a quick fix job, but replacing the right components makes all the difference. When everything is set up correctly again, the motor runs smooth and quiet like it should.

Key Features

• Precision Gear Engagement – Transfers power within the lower unit for smooth and reliable operation.
• Hardened Gear Construction – Built to handle load and resist wear under continuous use.
• OEM-Spec Machining – Designed to Yamaha tolerances for proper mesh and alignment.
• Consistent Power Delivery – Supports steady propulsion without slipping or grinding.
• Critical Drivetrain Component – Essential for proper gearcase function and long-term durability.

Engine & Boat Compatibility

Designed for Yamaha outboards with compatible lower unit and gearcase assemblies. Commonly used in small to mid-size engines found on fishing boats, skiffs, and recreational vessels. Always verify compatibility with your specific engine and gearcase before installation.

FAQ

Q: What are signs this gear is worn or damaged?
A: Grinding noises, slipping out of gear, or metal in the gear oil are common indicators.

Q: Can I replace just one gear or do I need a full rebuild?
A: It depends on wear—often multiple components are affected, so a full inspection is recommended.

Q: Is this a difficult repair?
A: Yes, gearcase work requires precision and proper setup, including shimming and alignment.

Q: What causes gear damage in a lower unit?
A: Impact, lack of lubrication, or water intrusion are the most common causes.

Q: Should I replace bearings and seals at the same time?
A: Absolutely, it’s best to service everything together while the gearcase is open.